You walk past the shelf and see it. A child, no more than three, is carefully removing the last cylinder from its block. Their brow is furrowed in concentration. They look at the empty hole, then at the cylinder in their hand. A moment of decision. With a gentle thud, it finds its home. https://bruinsmontessori.com/choosing-the-right-cylinder-block-set-for-your-montessori-classroom-in-the-usa/